Biodegradable absorbent articles

ABSTRACT

A biodegradable, disposable absorbent article, such as a diaper, having a non-woven inner layer of natural fibers and a non-woven outer layer of natural fibers and a treatment applied to at least one surface thereof. The treatment includes at least one compound selected from the group consisting of waxes, urethanes, silicones, fluorocarbons, and non-fluorochemical repellents. The absorbent article has a core of natural fibers or fibrous material, and optionally polyacrylate superabsorbent particles, positioned between the inner layer and the outer layer. The article may contain polylactic acid films between the layers.

FIELD OF THE INVENTION

The present invention relates to fluid-absorbing structures (absorbentarticles), such as diapers, incontinence products, feminine hygieneproducts, etc., and more particularly, relates to biodegradable,disposable absorbent articles, such as diapers, incontinence productsand feminine hygiene product, that are formed primarily of naturalfibers, e.g., cotton, and thus represent an eco-friendly (biodegradable)product.

BACKGROUND OF THE INVENTION

Articles used to absorb waste body fluids such as urine, blood, menses,and the like, are used in large quantities worldwide. These articles arecommonly referred to as being “absorbent articles”. Typically, thesearticles are in the form of diapers, and other like products, such as,feminine hygiene products and incontinence products, which have becomeincreasingly popular as a modern convenience and necessity.

Absorbent articles in the form of diapers generally come in twovarieties, namely, reusable cloth diapers and disposable diapers. Moderncloth diapers come with liners, including flushable liners, which holdthe waste and permit disposal into a toilet or the like. Disposablediapers greatly increased in popularity following the introduction ofsuperabsorbent polymers (SAP) in diapers in the mid-80s and today, anestimated 90% of U.S. parents use disposable diapers.

A basic disposable diaper includes the following components: (a) aninner layer or top sheet that sits next to the baby's skin and thus,serves as the initial layer that contacts waste fluids; (b) an absorbentcore that absorbs and holds the fluids (most absorbent cores are made offluff made from wood pulp fibers or corn/wheat based materials andinclude crystals (SAP) that are dispersed throughout the fluff such thatthe fluff serves to distribute the fluid, while the SAP is intended toabsorb the fluid and lock it in the core away from the baby); and (c) awaterproof outer shell or layer (back sheet) that provides a waterproofcoating/layer (this layer is most often made of some kind ofpetroleum-based plastic or plastic-treated material; however, some greendiaper companies are using plant-based plastic (aka bioplastic) toprovide this layer). The top sheet is most commonly prepared from woven,nonwoven, or porous formed-film polyethylene or polypropylene materials.Back sheet materials typically comprise flexible polyethylene sheetsalong with the film barrier. The back sheet can be formed as the samematerial as the top sheet; however, the back sheet includes the filmbarrier (that acts as a fluid barrier for leak proofing the diaper) onthe inner surface of the back sheet. The outer surface of the back sheetcomprises the back sheet material (e.g., nonwoven polyethylene) which issoft to the touch and the film barrier is concealed in a traditionaldiaper construction.

Due to the widespread use of disposable diapers, large quantities ofdisposable infant diapers are used each year and disposal of theseproducts is a problem. Most of the commercially available disposablediapers consist largely of plastics based on polypropylene andpolyethylene which do not break down in the environment, that is theyresist biodegradation totally.

In fact, the average disposable diaper can take 500 years to decomposeand contains petroleum, plastics, perfumes, wood pulp, and dioxins.

In particular, in many if not most disposable diapers, the liquidpermeable surface material and the leak-proof backing material are notbiodegradable, although the liquid absorbing material made of fluffedpulp exhibits biodegradability. Consequently, when the diaper isdisposed into the ground, the surface material and the backing materialremain without being degraded. For the purpose of complete disposal,therefore, it has been necessary to burn the whole diaper or to separatethe liquid-permeable surface material and the leak-proof backingmaterial from the top sheet layer for separate disposal.

A further difficulty associated with prior art disposable diapers isthat due to the large percentages of toxic chemicals in these products,rashes and skin allergies often arise in the user. Due to therequirements to maximize the absorbency of these products, thequantities of added toxic chemicals have been increased, furthercompounding the associated problems

Biodegradability and odor is an issue with the nonwovens industry,specifically for diapers, incontinence and feminine hygiene markets.Since the absorbent articles by nature are designed to absorb andcontain waste, one of the issues faced with using such products isunpleasant odors emanating from such products after they have becomesoiled. Odor control in absorbent products has been under investigationfor many years. Many body fluids have an unpleasant odor, or developsuch odors when in contact with air and/or bacteria for prolongedperiods. There is therefore a perceived need to create an improved odorcontrol agent that can be effectively incorporated into an absorbentarticle.

Other absorbent articles, such as feminine hygiene products andincontinence products, have similar constructions as the disposablediaper described above. There are no products currently on the marketthat meet the needs of those markets with non-antimicrobial protection.

Even though, a typical disposable diaper, for example, consists of asubstantial amount of biodegradable materials, e.g., wood pulp fibers,and the like, there is a need for reducing the amount ofnon-biodegradable materials in disposable absorbent articles. There is aparticular need to replace polyethylene back sheets in absorbentarticles with liquid impervious films comprised of biodegradablematerials, because the back sheet is typically the largestnon-biodegradable component of an absorbent article.

There is further a need to replace odor absorbing materials with thosemade of natural and/or biodegradable materials.

WO 2016/023016 A1 discloses a disposable diaper that is biobased and/orbiodegradable. The diaper is comprised of a biobased and/orbiodegradable outer sheet impermeable to aqueous medium, a biobasedand/or biodegradable inner sheet permeable to aqueous medium, andabsorbent pad made of natural fibers and biobased superabsorbents, andbiobased and/or biodegradable side sheets, fastening tabs and elasticwaist strip. In particular, the outer sheet, inner sheet, side sheets,fastening tabs and fastening mat are said to be made of a thermoplasticpolymer selected from the group consisting of aliphatic polyester,aromatic polyester, cellulosic fiber, nonwoven material and combinationsthereof. Superabsorbents can be cellulosic based, starch based orprotein based.

Biobased superabsorbent such as the cellulosic based, starch based orprotein based absorbents taught in WO 2016/023016 A1 tend to clump anddo not hold moisture as well as other materials that are not consideredas biobased, but are still biodegradable. Further, an issue with certainthermoplastic polyesters and cellulosic fibers, such as those disclosedin WO 2016/023016 A1, is that they do not degrade in all conditions.Accordingly, use of these materials in a natural fiber containing diapermakes it difficult, if not impossible, for them to pass biodegradabilitytests such as ASTM Test Method D5511-12, ASTM Test Method 5338.92 or ISOCD Test Method 14855. Applicant is unaware of any diaper productsactually able to pass any of ASTM D5511-12, ASTM Test Method 5338.92 orISO CD Test Method 14855.

What is desired, therefore, are biodegradable absorbent structures thatcan degrade in conditions in which oxygen is, or is not, present, i.e.both aerobic an anaerobic conditions. What is also desired is a diapercomprised entirely or substantially of biodegradable materials that iscompostable and/or will degrade in a landfill. In particular, it isdesired to have absorbent articles that are able to pass at least one ofASTM Test Method D5511-12, ASTM Test Method 5338.92 and ISO CD TestMethod 14855. It is further desired that a disposable diaper is able topass at least one of ASTM Test Method D5511-12, ASTM Test Method 5338.92and ISO CD Test Method 14855. It is further desired that such absorbentarticles and diapers contain odor absorbing materials made of naturaland/or biodegradable materials. It is also desired that any such diaperhave an outer layer that is impermeable to fluids yet has soft hand feelon its outward facing surface.

SUMMARY OF THE INVENTION

It is therefore an objective of the invention to provide a biodegradableabsorbent article that is comprised substantially of biodegradablematerials that will degrade in a landfill and/or through composting. Itis an object of the invention to provide absorbent articles that areable to pass ASTM Test Method D5511-12, ASTM Test Method 5338.92 and/orISO CD Test Method 14855.

It is further object of the invention that the biodegradable absorbentarticles are comprised of materials that degrade with and withoutoxygen.

It is particularly an object of the invention to provide biodegradablediapers that are able to pass at least one of ASTM Test Method D5511-12,ASTM Test Method 5338.92 or ISO CD Test Method 14855.

It is an object of the invention that biodegradable diapers have anouter layer that is impermeable to fluids yet has soft hand feel on itsouter surface.

It is further an object of the invention to provide biodegradableabsorbent articles, and in particular diapers, having odor absorbingmaterials made of natural and/or biodegradable materials.

In order to overcome the deficiencies of the prior art and to achieve atleast some of the objects and advantages listed, the invention comprisesa disposable absorbent article including a non-woven inner layercomprising natural fibers, a non-woven outer layer comprising naturalfibers and a treatment comprising at least one compound selected fromthe group consisting of waxes, urethanes, silicones, fluorocarbons,non-fluorochemical repellents applied to at least one surface thereof,and a core comprising natural fibers or fibrous material positionedbetween the inner layer and the outer layer. The absorbent article maybe a diaper, nappy, absorbent underpants, training pants, adultincontinence product, pet incontinence product, feminine hygieneproduct, wound dressing, or breast pad.

In some cases, the core comprises superabsorbent particles (SAP). Incertain preferred embodiments, the SAP is a polyacrylate.

In certain cases, the treatment is applied to the outer layer at 100% to200% by weight add on. In certain advantageous embodiments treatment isapplied at about 125% by weight add on. In some embodiments, thehydrophobic treatment is applied only to the top surface of the outerlayer. In certain other embodiments, the treatment is applied to thebottom and top surface of the outer layer.

In certain embodiments, the absorbent article further comprises anacquisition/distribution (ADL) layer between the inner layer and thecore. In some of those embodiments, the ADL is comprised of polylacticacid.

In some embodiments, the core comprises a corrugated structure definedby a plurality of peaks and valleys. In certain embodiments, the corecomprises a non-woven wrap surrounding loose fibers.

In certain preferred embodiments, the outer layer of the absorbentarticle is treated with a dendrimer wax. In some of those embodiments,the treatment is applied to a top surface of the outer layer. In someembodiments, the treatment is applied to a top and a bottom surface ofthe outer layer.

In certain embodiments of the absorbent article, the inner layerincludes a plurality of pores.

In some cases, at least one layer of the absorbent article includes adeodorizing composition comprising between about 0.1% and about 10% of azinc, copper, silver or aluminum salt. In some of those embodiments, theabsorbent article comprises about 0.1% and about 10% zinc rincinoleate.In certain of those embodiments, the composition further comprises atleast one compound selected from the group consisting of ethoxylatedalcohols, ethoxylated glycols, ethoxylated oils, polymers or co-polymersof acrylic acid and combinations thereof and at least one drying agentselected from the group consisting of primary, secondary, and tertiaryalcohols and combinations thereof.

In some embodiments, the absorbent article is biodegradable in that itpasses at least one of ASTM Test Method D5511-12, ASTM Test Method5338-15, and ISO CD Test Method 14855-1:2012.

The invention also comprises a biodegradable diaper comprising anon-woven inner layer comprising cotton, an outer layer comprisingcotton treated with a hydrophobic agent selected from the groupconsisting of waxes, urethanes, silicones, fluorocarbons, andnon-fluorochemical repellents and combinations thereof, and an absorbentcore comprising cotton and a polyacrylate superabsorbent particlespositioned between the inner layer and the outer layer.

In some embodiments, the inner layer of the diaper comprises a pluralityof pores.

In certain advantageous embodiments, the diaper further comprises apolylactic acid film disposed between at least one of the core and theouter layer or the core and the inner layer. In some of thoseembodiments, a PLA film is disposed between both the inner layer and thecore and the outer layer and the core. In other of those embodiments, aPLA film is disposed between the outer layer and the core.

In some cases, the diaper has a treatment consisting of dendrimer waxapplied to the outer layer. In certain of those cases, the treatment isapplied to the outer layer at 100% to 200% by weight add on. In certainadvantageous embodiments the dendrimer wax is applied at about 125% byweight add on. In some embodiments, the hydrophobic treatment is appliedonly to the top surface of the outer layer.

In certain embodiments, the diaper further comprises a pair of lateralflaps extending from a rear portion of the outer layer, said flapsincluding polylactic acid hook fasteners capable of affixing the flapsto loops on a front portion of the outer layer.

In some embodiments, the diaper is biodegradable in that it passes atleast one of ASTM Test Method D5511-12, ASTM Test Method 5338-15, andISO CD Test Method 14855-1:2012.

Other objects of the invention and its particular features andadvantages will become more apparent from consideration of the followingdrawings and accompanying detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an absorbent article in the form of adiaper made in accordance with the present invention;

FIG. 2 is a close-up of a portion of an inner layer of the diaperaccording to one embodiment;

FIG. 3 is a cross-sectional view of a diaper according to a firstembodiment;

FIG. 4A is a cross-sectional view of a diaper according to a secondembodiment;

FIG. 4B is a cross-sectional view of a diaper according to a thirdembodiment;

FIG. 5 is a cross-sectional view of a diaper according to a fourthembodiment;

FIG. 6 is a side view of an absorbent core according to one embodiment;

FIG. 7 is a top perspective view of a diaper according to a fifthembodiment showing the various layers/components thereof including acore wrap that can optionally be in the form of a corrugated structure;

FIG. 8 is a top plan view of the diaper of FIG. 7 in an assembled state;and

FIG. 9 is a front elevation view of the diaper of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions and methods are provided to better define thepresent disclosure and to guide those of ordinary skill in the art inthe practice of the present disclosure. Unless otherwise noted, termsare to be understood according to conventional usage by those ofordinary skill in the relevant art.

As used in the description, the terms “top,” “bottom,” “above,” “below,”“over,” “under,” “above,” “beneath,” “on top,” “underneath,” “up,”“down,” “upper,” “lower,” “front,” “rear,” “back,” “forward” and“backward” refer to the objects referenced when in the orientationillustrated in the drawings, which orientation is not necessary forachieving the objects of the invention.

As used herein the term “nonwoven” fabric or web means a web having astructure of individual fibers or threads which are interlaid, but notin an identifiable manner as in a knitted or woven fabric. Nonwovenfabrics or webs can be formed by various processes including, but notlimited to, meltblowing processes, spunbonding processes, spunlacingprocesses and bonded carded web processes.

As used herein the term “spunbond fibers” refers to small diameterfibers of mechanically and/or eductively drawn polymeric material.Spunbond fibers are generally formed by extruding molten thermoplasticmaterial as filaments from a plurality of fine capillaries of aspinneret with the diameter of the extruded filaments then being rapidlyreduced. Examples of spunbond fibers and methods of making the same aredescribed in, by way of example only, U.S. Pat. No. 4,340,563 to Appelet al., U.S. Pat. No. 5,382,400 to Pike et al., and U.S. Pat. No.5,795,926 to Pike et al.; the entire content of the aforesaid patents ishereby incorporated by reference herein. Spunbond fibers are generallynot tacky when they are deposited onto a collecting surface and arecontinuous.

As used herein “spunlaced fibers” refers to those made by a processinvolving the cohesion and the interlacing of the elementary fibers withone another is by means of a plurality of jets of water under pressurepassing through a moving fleece or cloth and causing the fibres tointermingle with one another. As an example, a process for theproduction of spunlaced nonwoven cloths has been described in U.S. Pat.Nos. 3,214,819, 3,485,706 and 3,508,308; the entire content of theaforesaid patents is hereby incorporated by reference herein.

As used herein the term “meltblown fibers” means fibers of polymericmaterial which are generally formed by extruding a molten thermoplasticmaterial through a plurality of die capillaries as molten threads orfilaments into converging high velocity air streams which attenuate thefilaments of molten thermoplastic material to reduce their diameter.Thereafter, the meltblown fibers can be carried by the high velocity gasstream and are deposited on a collecting surface to form a web ofrandomly dispersed meltblown fibers. Meltblowing processes are disclosedin, by way of example only, in U.S. Pat. No. 5,271,883 to Timmons etal.; U.S. Pat. No. 5,160,746 to Dodge et al.; U.S. Pat. No. 4,526,733 toLau; U.S. Pat. No. 5,652,048 to Haynes et al.; and U.S. Pat. No.5,366,793 to Fitts et al.; the entire contents of the aforesaid patentsare hereby incorporated by reference herein. Meltblown fibers aregenerally smaller than about 10 micrometers in average diameter and,unlike spunbond fibers, are generally tacky when deposited onto acollecting surface, thereby bonding to one another during the depositionstep.

As used herein the term “biodegradable” is meant to represent that amaterial degrades from the action of naturally occurring microorganismssuch as bacteria, fungi, and algae. The biodegradability of a materialmay be determined using ASTM Test Method D5511-12 for anaerobicbiodegradation of plastic material in high-solids anaerobic conditions,ASTM Test Method 5338-15 for aerobic biodegradation of plastic materialsunder controlled composting conditions, or ISO CD Test Method14855-1:2012 or other suitable and applicable standards. The contents ofASTM Test Method D5511-12, ASTM Test Method 5338.92 and ISO CD TestMethod 14855-1:2012 are incorporated herein in their entirety byreference.

The word “disposable” is used in the specification to describe absorbentarticles that are not intended to be laundered or otherwise restored orreused as an absorbent article. They are intended to be discarded aftera single use and preferably to be disposed of in an environmentallyfriendly manner.

The phrase “personal product” is intended to include products orarticles used to absorb waste body fluids or other body waste, andincludes diapers, nappies, absorbent underpants, training pants, adultincontinence products, pet incontinence products, feminine hygieneproducts, wound dressings, and breast pads. It will be appreciated thatthe above list is not limiting and the teachings of the presentinvention can be implemented into other types of absorbent products thatare intended for fluid absorption.

FIGS. 1 and 3 illustrate an absorbent article (personal product) 100according to one exemplary embodiment and, in particular, the absorbentarticle 100 is in the form of a disposable diaper for an infant (baby).It will be understood that the illustrated diaper 100 is only anexemplary embodiment and the teachings of the present invention can beimplemented in a toddler training pant/diaper or other similar absorbentproducts, as well as the other absorbent products mentioned herein. FIG.1 is a perspective view of the diaper 100, while FIG. 3 is across-sectional view of the diaper 100.

The diaper 100 is formed generally of an inner layer (top sheet) 200, aninner acquisition/distribution layer and/or absorbent core 300 and anouter shell or cover (back sheet) 400.

Inner Layer

As previously mentioned, the inner layer 200 plays an important role inthe construction of the diaper since the inner layer 200 is the layerthat is next to the most sensitive area of the baby's body, sometimesfor hours at a time. The quality and makeup of the inner layer 200 layeralso determines the level of absorbency and comfort (softness) for thebaby.

In accordance with the present invention, the inner layer 200 is formedfrom natural fibers (e.g., 100% organic, natural cellulosic fibers).More specifically, the inner layer 200 comprises a non-woven fabric(material) that is formed from natural fibers. Any number of differentnatural fibers can be used to form the non-woven inner layer 200 so longas they are suitable for the intended use described herein. Exemplarynatural fibers, include but are not limited to, both plant-based naturalfibers and animal-based natural fibers. Plant-based natural fibersinclude, but are not limited to, cotton, hemp, flax, ramie, bamboo, etc.

Cotton is the most widely used natural fiber and is very absorbent, easyto care for, and comfortable for babies. Cotton is almost pure celluloseand is both soft to the touch and advantageously has breathability. Aswith many materials, cotton is available and marketed in an organic formwhich is generally understood to mean that the cotton is grown fromnon-genetically modified plants without the use of any syntheticagricultural chemicals, such as fertilizers or pesticides.

Hemp fiber comes from the plant species cannibus sativa. Hemp is nottypically certified organic, but its production is considered organic bydefinition. Hemp grows quickly and does not require the use offertilizer or pesticides. When used in diapers, hemp is quite absorbent,thick, and durable.

Bamboo is a sustainable crop; its quick growth allows it to be replacedquickly with a new crop. Like hemp, it does not typically requirefertilizers or pesticides to grow. Bamboo is nice for diapering becauseit is soft and very absorbent.

Animal-based natural fibers include, but are not limited to, wool. Asdescribed herein, wool is more particularly suited as a material to formthe outer shell (back sheet) 400 since wool-based covers work very wellat containing leaks and allowing air to circulate. Organic wool containsno pesticide residue and the sheep are raised organically.

In addition, rayon (e.g., viscose rayon), which is a natural-basedmaterial made from the cellulose of wood pulp, is also suitable as theinner layer material.

In addition, the inner layer 200 can be formed from biopolymers whichare biodegradable. For example, polylactide biopolymers offer arenewable and biodegradable or recyclable alternative topetrochemical-based fibers.

It will also be appreciated that the inner layer 200 can be formed as ablend of two or more of the above-mentioned natural materials.

Most cotton-based personal products are formed of layers that are formedusing spunbond or spunlaced fibers. However, it is possible to usethermal bonded nonwovens, which are softer but have lower resistance andstrength, and trough air bonded nonwovens, which are more lofty, canalso be used.

The inner layer 200 can be either hydrophilically treated or can behydrophobically treated and in particular, the non-woven materialforming the inner layer 200 can undergo a surface treatment using atreatment composition which either imparts hydrophilic properties orhydrophobic properties. Any number of different surface treatments canbe used to impart increased hydrophilicity to the nonwoven fabric. Forexample, chemicals, such as surfactants, wetting agents and rewettingagents can increase the hydrophilic nature of the material and can makea fabric that is naturally hydrophobic into one that is hydrophilic.With respect to fibers, natural fibers tend to be hydrophilic,especially when natural oils have been removed from them. The surfacetreatment can be performed using any number of suitable techniques andmore specifically, conventional treatments involve steps such as dippingthe nonwoven in a treatment bath, coating or spraying the nonwoven withthe treatment composition, and printing the nonwoven with the treatmentcomposition.

When a nonwoven web is formed of a hydrophobic material or otherwiseexhibits hydrophobic properties, it is often desirable to modify thesurface of the nonwoven web using a hydrophilic surfactant to increasethe wettability of the web. An external hydrophilic surfactant istypically applied to the surface of the nonwoven web. An internalhydrophilic surfactant is typically blended with the material (e.g.,cellulose fibers) used to form the nonwoven web, and later migrates tothe surface after the nonwoven web is formed. External and internalhydrophilic surfactants may be characterized in terms of theirdurability and wettability. The durability of a surfactant refersgenerally to its ability to withstand stresses, such as repeated washingcycles of the nonwoven fabric, without being removed from the fabric orotherwise losing its effectiveness. The wettability of a surfactantrefers generally to its ability to transform a hydrophobic nonwoven webinto a fabric which readily assimilates and distributes aqueous liquids.Surfactants which cause an otherwise hydrophobic nonwoven web toassimilate liquids at a relatively fast pace, with high fluid intakevolumes, are referred to as faster wetting surfactants. Surfactantswhich cause the nonwoven web to assimilate aqueous liquids at arelatively slow pace, with low fluid intake volume, are referred to asslower wetting surfactants.

The surface treatment is thus configured to increase the hydrophilicnature of the nonwoven by reducing the surface tension of the nonwoven,reducing the contact angle with the liquid and allowing the fluid topass. As described below, flow dynamics within the acquisitionlayer/absorbent core 300 prevent liquids from returning to the surface.

FIG. 3 shows a surface treatment 205 applied to a top surface of theinner layer 200, i.e. the surface in contact with skin; FIGS. 4A and 4Bshow surface treatment 206 applied to the bottom surface of the innerlayer, i.e. the surface closer to the core; and FIG. 5 shows yet anotherembodiment in which the surface treatment 205, 206 is applied to boththe top and bottom surfaces of the inner layer 200.

It will also be understood that the surface treatment applied to theinner layer 200 can be configured as a finish that is biodegradable andimparts hydrophobic properties on one side and hydrophilic properties onthe other side.

In preferred embodiments, the inner layer 200 comprises a polylaticacid(PLA) treatment 206 applied to the bottom surface, i.e. the surfacecloser to the core. Alternatively, the PLA is provided as a film 206that is adhered to the bottom surface of the inner layer and/or the topsurface of core 300 and can serve as an ADL as discussed further below.

As shown in FIGS. 7-9, in certain embodiments, the inner layer comprisesa plurality of openings or pores, such as those provided in a gauze-likematerial. These openings readily allow for the passage of fluid into aninner acquisition/distribution layer and/or absorbent core 300 so thatfluid is not retained on the surface of the inner layer that touches theskin.

The nonwoven inner layer 200 can be formed by any number of suitableprocesses including, but not limited to, hydroentanglement, carding,air-laying, thermal treatment, or other suitable process. Pores, a dotmatrix, or perforations can be created during the nonwoven formationprocess or can be applied to the nonwoven after formation. Any number ofmeans can be employed to create these openings in a pre-formed nonwoven,including but not limited to air jet formation, laser formation, duringextrusion or casting, or by passing a sheet through a roller millwherein the rollers have microspikes suitable for forming pores on thesheet. Additionally, a porous sheet can be formed by incorporatingmicroparticles of a water soluble substance and passing the sheetthrough a water bath after its formation. The water dissolves themicroparticles so as to produce pores. In particularly preferredembodiments, the pores are structurally built during cotton sheetformation.

The openings or pores 210 in the inner layer may be any shape thatallows the passage of fluid, preferably oval or round. The openings aretypically between about 0.10 cm and about 0.25 cm in diameter.Preferably, the pores of the inner layer are 0.15 cm to 0.15 cm indiameter. Most preferably, the pores are 0.15 cm to 0.12 cm in diameter.

Surface Pattern for the Inner Layer

The inner layer 200 can be formed so as to have a surface pattern(surface modification) 201 that is formed as a part thereof. FIG. 2shows one exemplary surface pattern 201 that generally has a dot matrixformation of slight protrusions across the exposed surface of the innerlayer 200 in at least one region. It will be appreciated that theprotrusions that define the surface pattern 201 can take any number ofdifferent forms, sizes, and shapes and thus, are not limited to thecircular ones shown in FIG. 2.

The surface pattern 201 is constructed to provide fluid channeling inthat fluid (e.g., urine) that is discharged onto the inner layer 200flows into the channels/spaces that are formed between the surfacemodification features and away from the skin of the infant. It willtherefore be appreciated that the surface pattern 201 is thus preferablyprovided at least in areas that are prone to receiving fluid, such asthe central portion of the inner layer 200. Thus, the surface pattern201 can be formed locally on one or more regions of the inner layer 200or can be formed across at least substantially the entire surface of theinner layer 200.

It will also be understood that the surface pattern 201 can be formed ofat least two different types of surface modification features, such asfeatures that have different shapes and/or sizes.

Inner Acquisition/Distribution Layer (ADL) and Absorbent Core Structure

The diaper 100 can be formed to have a distinct acquisition/distributionlayer and absorbent core or can be formed to have a single innermoststructure that acts as the absorbent storage structure. When two or morelayers are present, the acquisition/distribution layer is the layerunder the inner layer (topsheet) 200 of the diaper 100. It moves liquidaway from the baby's skin and distributes it more evenly across theentire diaper core for better absorbency. When the diaper 100 includesthe inner layer 200 and a separate acquisition/distribution layer, alongwith an absorbent core structure, the acquisition/distribution layer maybe formed of natural fibers, such as a nonwoven cotton material, anddoes not include SAP. The ADL can thus acquire a surge of fluid withinthe absorbent product until the superabsorbent particles (SAP) in theabsorbent core structure can absorb the retained fluid out of thecellulose-based ADL and in the final storage site (absorbent corestructure) containing the superabsorbent particles.

The type of personal product (absorbent article) may dictate whether ornot there is a separate acquisition/distribution layer relative to theabsorbent core.

The absorbent core structure is the innermost layer of the diaper andrepresents a storage layer (structure) that absorbs and stores theliquid acquired from the top layer(s) (e.g. inner layer and/oracquisition/distribution layer). The absorbent core structure is made upof an absorbent core (inner absorbing material) and preferably, alsoincludes an absorbent core wrap that surrounds and contains theabsorbent core. The absorbent core wrap thus encapsulates the absorbentcore (inner absorbing material). FIGS. 3-5 depict embodiments in whichthere is only an absorbent core 300 disposed between the inner layer 200and the back sheet 400. In this arrangement and others disclosed herein,the various layers can be bonded to one another using suitable bondingagents, such as adhesives (e.g., biodegradable glue products). Asdescribed below and shown in FIG. 7, in a different embodiment, adistinct absorbent core wrap is used to contain the material forming theabsorbent core.

The absorbent core typically consists of a blend of fluff cellulosefibers and SAP (e.g., polyacrylate granules). In accordance with thepresent invention, the fluff cellulose material is in the form of cottonand in particular, can be in the form of loose, fluff cotton. It will beappreciated as mentioned herein, that other natural materials (e.g.,bamboo, fluff pulp, etc.), described herein, can be used as the materialof the ADL and/or absorbent core (inner material).

The cellulose material quickly absorbs and transfers fluid (e.g., urine)to the superabsorbent polymer material (SAP), where it is trapped. Thiskeeps the baby's skin dry, even if he or she sits on a full diaper.Since the superabsorbent polymers absorb many times their weight influids, children's skin health is improved because these polymers lockmoisture away where it cannot irritate skin. The severity and frequencyof diaper rash has declined dramatically.

As used herein, “superabsorbent polymer” or “SAP” means any suitablehydrophilic polymer that can be mixed with fibers of the presentinvention. A superabsorbent polymer is a water soluble compound that hasbeen cross-linked to render it water insoluble but still swellable to atleast about 15 times its own weight in physiological saline solution.These superabsorbent materials generally fall into 3 classes, namelystarch graft copolymers, cross-linked carboxymethylcellulosederivatives, and modified hydrophilic polyacrylates. Examples ofabsorbent polymers include hydrolyzed starch-acrylontrile graftco-polymer, saponified acrylic acid estervinyl co-polymer, modifiedcross-linked polyvinyl alcohol, neutralized cross-linked polyacrylicacid, cross-linked polyacrylate salt, and carboxylated cellulose. Thepreferred superabsorbent materials, upon absorbing fluids, formhydrogels.

The superabsorbent polymer materials have relatively high gel volume andrelatively high gel strength as measured by the shear modulus of thehydrogel. Such preferred materials also contain relatively low levels ofpolymeric materials which can be extracted by contact with syntheticurine. Superabsorbent polymers are well-known and are commerciallyavailable. One example is a starch graft polyacrylate hydrogel marketedunder the name IM1000 (Hoechst-Celanese, Portsmouth, Va.). Othercommercially available superabsorbent polymers are marketed under thetrademark Sanwet (Sanyo Kasei Kogyo Kabushiki, Japan), Sumika Gel(Sumitomo Kagaku Kabushiki Haishi, Japan), Favor (Stockhausen,Garyville, La.) and the ASAP series (Chemdal, Aberdeen, Miss.).Superabsorbent particulate polymers are also described in detail in U.S.Pat. No. 4,102,340 and U.S. Pat. No. Re. 32,649. An example of asuitable SAP is surface cross-linked acrylic acid based powder such asStockhausen 9350 or SX FAM 70 (Greensboro, N.C.). The SAP can come fromany number of other sources. Other suitable SAP materials are disclosedbelow.

In embodiments in which the absorbent core structure includes a distinctabsorbent core wrap (FIG. 7), the absorbent core wrap comprises a fabriclayer (e.g., a nonwoven layer) that contains the absorbent core (innerabsorbing material). As described herein, the absorbent core wrap can beformed of the biodegradable materials disclosed herein. For example, theabsorbent core wrap can be in the form of a nonwoven cotton fabric orcan be formed of a paper material. Additional details of the absorbentcore wrap is described below.

In accordance with one embodiment of the present invention, the inneracquisition layer/absorbent core structure 300 includes a 100% cottonfluff material, such as a 100% cotton fluff blend (for the absorbentcore). The thickness of the layer 300 is typically greater than theinner layer 200 since the layer 300 acts as the storage (collection)layer beneath the thinner inner layer 200. When there is a separateacquisition/distribution layer relative to the absorbent core structure,the absorbent core structure typically has a greater thickness comparedto the acquisition/distribution layer.

As is known, SAPs are made from partially neutralized polyacrylic acidwhich is lightly cross-linked throughout small beads to form aninsoluble, hydrophilic gel. In one exemplary embodiment, the SAP used inthe layer 300 (as absorbent core) includes minimal (light) to nocross-linking (between the shells). The SAP is dispersed throughout thecotton fibers that form the absorbent core of the absorbent corestructure 300.

In contrast to other SAP that is used in commercial products, the SAPthat is particularly suited for use in the present absorbent articlescomprises a 100% acrylic acid co-acrylamide with little to no cross linkshell. Since the absorbent articles described herein are preferably atleast substantially biodegradable, the SAP needs to have an at leastsubstantially shell-less structure. Consequently, there is little to nocross link shell in the SAP structure. An alternative SAP structure canbe a blend of acrylic acid co-acrylamide with little to no cross-linkshell with an organic absorbent material, such as corn starch. Thepercentages of these two components in the blend can vary depending uponthe particular application and in particular, the inclusion ofcornstarch is preferably at a sufficient amount to encourage moisturetransfer from one acrylate molecule to an adjacent acrylate molecule.

In yet another embodiment, the absorbent core (inner absorbing material)can be formed of 100% cornstarch combined with cotton lint (cottonfibers, etc.). Alternatively, the absorbent core can include 100% clay(attapulgite which is technically magnesium aluminum phyllosilicate(MgAl)2Si401O(OH)+4 H20).

Corrugated Shape

As described herein, to perform its function, the absorbent corestructure 300 of the absorbent article (diaper 100) should be capable ofintaking large volumes of fluid rapidly, with some control. In thiscase, the absorbent material necessarily requires a large amount of voidspace to take in a fluid insult (surge), but needs the appropriatestructural characteristics in controlling, spreading, and retaining thefluid.

In one exemplary embodiment and as shown in FIG. 6, the absorbent corestructure of layer 300 is a corrugated absorbent structure 301 having aplurality of alternating peaks and valleys for use in absorbentarticles. It will be appreciated that the corrugated absorbent structure301 includes the absorbent core (inner absorbent material) and theabsorbent core wrap, if present.

The corrugated absorbent core structure provides improved fluid intakedue to the higher material surface area for fluid contact, void volumecreated by the corrugation process, a visual cue for improved fluidintake due to the improved material aesthetics, improved absorption offluids, such as urine, menses and bowel movement due to the surfacestructure of material which provides “pockets” for intake, and softnessand dryness due to the modified surface topology of the corrugatedabsorbent material providing reduced contact with the skin of theinfant.

As shown in FIG. 6, the corrugated structure 301 of one embodimentcomprises a plurality of alternating peaks 303 and valleys 305. Theabsorbency properties of the layer 300 depends on the frequency of peaks303 and valleys 305 and can be measured as being in a range of about oneper a first predetermined length of material to about one per a secondpredetermined length of material. The peaks 303 and valleys 305 can haveany number of different shapes including rounded shaped, a triangularshape where they come to a sharp point, or a plateau shape where thepeaks and valleys are relatively flat. It will also be apparent that,for some applications, a combination of shapes may be desirable.Additionally, these corrugations may be zoned in the product andlocalized in strategic places for different functionality. For thisreason, the combination of peak frequencies and heights may be varieddepending upon the effect being pursued.

To promote rapid fluid intake by the corrugated nonwoven material 301,it may be desired that the surfaces of the material or the surface ofthe fibers forming the material be first wetted by the liquid.Wettability of nonwoven materials or fibers thereof is known to beachievable by treating the surface thereof with surfactants. See, forexample, U.S. Pat. No. 4,413,032 to Hartmann et al. and U.S. Pat. No.5,045,387 to Schmalz.

Fluid intake benefits may be enhanced by treating the corrugatedmaterial 301 with a surfactant in a manner which produces wettabilitygradients within the material. A surfactant treatment can be applied tothe valleys 305 of the corrugated structure 301 so as to aid in drawingfluid away from the peaks 303 (material surface), i.e. z-directed flow,of the corrugated structure 301. To further enhance the flow of fluidaway from the material surface, the peaks 303 of the material may bedesigned to be hydrophobic. Similar functionality may also be achievedby applying a treatment to the lower surface of the corrugated structure301. A wettability gradient for enhancement of fluid intake may also beeffected by incorporating alternate raw materials, for example fluffpulps (e.g., fluff cotton) with different wettability properties, indual or multi-layered configurations.

The use of the corrugated absorbent material of this invention is notlimited to the fluid intake layers of the absorbent articles. It mayalso be applied to fluid distribution layer for desorption, dryness andconformance improvements.

Outer Layer (Back Sheet)

The back sheet or cover 400 is the outer layer of the diaper 100 and isconstructed to prevent liquids from leaking out of the diaper 100. Theback sheet 400 thus acts as a fluid barrier. In accordance with thepresent invention, the back sheet 400 is also formed from naturalmaterials so as to be biodegradable and in particular, is a nonwovenstructure formed from natural fibers, such as those listed herein. Inone exemplary embodiment, the back sheet 400 is a nonwoven cottonstructure that is constructed to provide a fluid impervious layer.

The back sheet 400 can be hydrophobically treated and in particular, thenonwoven material forming the back sheet 400 can undergo a surfacetreatment using a treatment composition which either imparts hydrophobicproperties. Any number of different surface treatments can be used toimpart increased hydrophobicity to the nonwoven fabric. For example,certain agents can increase the hydrophobic nature of the material andmore particularly, materials, such as urethanes, silicones,fluorocarbons, non-fluorochemical repellents and waxes, can imparthydrophobic properties. The surface treatment can be performed using anynumber of suitable techniques and more specifically, conventionaltreatments involve steps such as dipping the nonwoven in a treatmentbath, coating or spraying the nonwoven with the treatment composition,and printing the nonwoven with the treatment composition.

In some embodiments, the treatment may comprise Finish RPW dendrimer waxdispersion, Nylwick (or Nylwck) modified water dispersible polyesterwith ethoxylated alcohols, Aquatek Uno sulfonated nylon, Block Ssulfonated nylon, WSR XF non-fluorine water repellant, NF-21 fluorinated(C6) surfactant, HCO16 and/or ethox 2191. A particularly preferred formis provided as Finish Nylwck by Phoenix Chemical Company. In certainpreferred embodiments, the treatment may comprise Permaseal WSR-XF C6fluorocarbon and/or Flexiwet NF non-fluorocarbon silicon waterrepellant.

In certain embodiments, the hydrophobic treatment comprises dendrimerwax. In certain of those embodiments, the treatment comprises RPW.Dendrimer waxes typically used in the invention are available in liquidform and can be applied to nonwoven materials by a number of techniquesreadily known in the art. An advantage of wax based treatments, andparticularly dendrimer wax treatments, is that they degrade with andwithout oxygen. Accordingly, absorbent articles treated with these waxesare able to pass ASTM Test Method 5338.92.

The treatment is applied to the natural fibers at 100% to 200% byweight. In some embodiments, 100% to 150% by weight of the treatment isapplied. In certain of those embodiments, about 125% by weight of thetreatment is applied. In particularly preferred embodiments, 100% to130% by weight of the treatment is applied to fabric. In some of thoseembodiments, e.g. where a dendrimer wax is used, about 120% to 125% byweight of the treatment is applied to fabric by weight. It is importantthat at least 100% add on by weight of the hydrophobic treatment isapplied to the outer layer. It is believed that use of lower levels ofsuch ingredients will allow the treated fabrics to retain hydrophiliccharacteristics, as opposed to the water resistant and water repellantproperties imparted by higher concentrations of such chemicals tofabrics.

In some particularly preferred embodiments, the invention comprisesapplying about 125% by weight of Finish RPW dendrimer wax to a nonwovencotton or cotton elastomeric blend. In particular, it is advantageous toapply a treatment comprising dendrimer wax or a dendrimer wax emulsionto the inside (top) surface of the outer sheet.

As used herein, the terms “percent”, “%,” “weight percent” and “wt %”all mean the percentage by weight of the indicated component oringredient within the product or composition in which it is present,without dilution, unless otherwise indicated by the context in which theterm is used. When the treatment is applied to a fabric, the percent”,“%,” “weight percent” and “wt %” refers to the amount applied to thefabric upon drying unless otherwise stated.

Treatment solutions and suspensions comprise various percentages byweight of the treatment compositions in water unless anothersolvent/diluent is indicated.

An external hydrophobic agent is typically applied to the surface of thenonwoven web. An internal hydrophobic agent is typically blended withthe material used to form the nonwoven web, and later migrates to thesurface after the nonwoven web is formed. External and internalhydrophobic agents can be characterized in terms of their durability andwettability similar to hydrophilic agents as described above.

FIG. 3 shows a surface treatment 405 applied to the bottom surface ofthe back sheet 400, i.e. the surface away from the core; FIG. 4A showssurface treatment 406 applied to the top surface of the back sheet, i.e.the surface closer to the core; FIG. 4B shows a surface treatment 407applied to the top surface of the back sheet; and FIG. 5 shows yetanother embodiment in which the surface treatment 405, 406 is applied toboth the top and bottom surfaces of the back sheet 400.

It will therefore be appreciated that there are other combinations forthe surface treatments 205, 206, 405, 406, 407 that are not shown in thefigures. For example, the surface treatment 206 can be on the topsurface of the nonwoven layer 300 and surface treatment 406 can be onthe top surface of the nonwoven layer 400. Similarly, the surfacetreatment 406 can be on the bottom surface of the nonwoven layer 300 andsurface treatment 405 can be on the bottom surface of the nonwoven layer400. As another example, the surface treatment 406 can be on the bottomsurface of the nonwoven layer 300 and surface treatment 406 can be onthe top surface of the nonwoven layer 400. As yet another example,treatment 407 can be provided as a film that is adhered to the bottomsurface of nonwoven layer 300 and also adhered to the top of treatment406, which is applied to the top surface of layer 400.

In certain preferred embodiments, hydrophobic surface treatments 405,406 comprise a wax, a non-fluorocarbon repellant, or a combinationthereof. An example of a wax that may be used to treat the back layer isFinish RPW available from Phoenix Chemical. An example of anon-fluorocarbon repellant that may be used to hydrophobically treat theback layer is WSRXF available from Phoenix Chemical.

In some embodiments, the treatment 406 is separated from the layer 300by a thermoplastic polyester, such as a PLA film. The film may beadhered to layer 300 and treatment 406. In other embodiments, a PLA filmis adhered to the top of layer 400 and hydrophobic treatment isincorporated into or on the bottom of layer 400. Incorporation of a PLAinto or on a surface of layer 400 facilitates printing of designs ontothe outer layer.

Leg Cuffs, Waistband and Fasteners

As shown in FIG. 1, a rear portion 107 of the diaper 100 that defines apreferably stretchable waistband 110 includes a pair of lateral flaps120 that each contains a refastenable fastener 122 to allow therespective lateral flap 120 to be attached to the front portion 109 ofthe diaper 100. The lateral flaps 120 can extend laterally and outwardlyfrom side panels that are formed at the rear portion 107. The sidepanels can be formed to have a degree of stretch along with thewaistband portion of the rear portion 107 that is disposed between theside panels. As described herein, the stretch portions of the rearportion 107 and any other portion of the diaper 100 can include anelastic member to provide for such stretching to accommodate differentsized infants and ensure a tight fit (seal) between the diaper 100 andthe infant.

The flaps 120 can be in the form of cotton tape with an adhesive layer,such as a glue. Instead of glue, other refastenable fasteners may beused, such as hook and loop mechanical fasteners or other suitablefasteners. As part of a total biodegradable absorbent article, abiodegradable glue can be used.

The front portion 109 includes a pair of tabs 140 which are placed inregistration with the lateral flaps 120 when the rear portion 107 isattached to the front portion 109. To fasten the front portion 109 tothe rear portion 107, the user simply removes the protective sheet thatcovers the adhesive layer (glue layer) to expose the adhesive and thenonce a proper, snug fit is achieved, the flaps 120 are attached to thefront portion 109 (e.g., to the tabs 140).

In other embodiments, the flaps 120, tabs 140 and/or fasteners 122 maybe comprised of polyesters or polypropylenes, preferably derived fromplant based materials. In certain embodiments, the flaps 120, tabs 140and/or fasteners 122 may be comprised of a biodegradable polymericmaterial such as polylactic acid or polyhydroxyalkanotes such aspolydroxybutyric acid (PHB). Preferably, the fasteners 122 are comprisedof PLA and comprise hook and loop structures also comprised of PLA. Thehooks are placed on flaps 120 while loop structures can be placed, forinstance on a strip 112, on the front portion. PLA fasteners and tabsmay be adhered to the other components of the diaper by a numbers ofmeans known in the art, such as by using a glue, thermal bonding orultrasonic welding.

The diaper also includes a pair of leg cuffs 500 that are designed toeffectively prevent leakage at the sides of the diaper 100, therebykeeping the infant's skin dry and protected. In some embodiment, the legcuffs 500 can be constructed a set of inner standing leg cuffs and alsobe referred to and known as gathers. As shown in FIG. 1, the leg cuffs500 are generally formed in the central portion of the diaper 100.

In one exemplary embodiment, each leg cuff 500 is formed of a nonwovencotton structure with a rubber inlay to provide the desired elasticity.When the diaper 100 includes a defined elastic waistband, it too can beformed as a nonwoven cotton structure with a rubber inlay to provideelasticity thereto. Biodegradable rubber or natural rubber can be usedfor any elastic element that is part of the absorbent article.

It will be appreciated that the elastic structure can be formed of othermaterials, such as spandex and other synthetics. As mentioned herein,the elastic structures are used in cuffs, for the waist and the legs andalso they can be used in lateral side panels and in tape construction.Many gasketing cuffs use spandex to provide a seal with the infant'slegs.

In preferred embodiments, the leg cuffs 500 are comprised ofpolypropylene, ethylene, spandex or a combination thereof.

Anti-Odor Technology

In some embodiments in accordance with the present invention, theabsorbent products can have anti-odor technology incorporated into thestructure thereof. For example diaper 100 can include the anti-odortechnology. Anti-odor technology can be built into adult incontinentproducts so the wearer does not have to worry about being embarrassed bythe odors associated with incontinence. It will be understood that theanti-odor technology described herein is optional and the absorbentproducts described herein (e.g., diaper 100) can be formed without suchfeature.

As described herein, the anti-odor technology can be incorporated intoone or more layers/structures of the diaper 100 to provide the desiredanti-odor properties.

A first anti-odor technology is directed to methods to disruptunpleasant odors through bond destruction, thereby de-volatizingmolecules in nonwovens, a second anti-odor technology is directed tomethods to impart non-hydrocarbon pleasant fragrances to nonwovens, anda third anti-odor technology is directed to methods to disruptunpleasant odors in non-wovens while binding volatilized hydrocarbonsusing synthetic chemistry and softening agents.

Technology is used to disrupt unpleasant odors through bond destruction,thereby de-volatizing molecules in nonwovens. Bond destructingtechnology, such as the use of various high performance salts, can beused to disrupt unpleasant odors emanating from the absorbent product.For example, zinc salts of ricinoleic acid are highly effective activedeodorizing substances. The effectiveness of zinc ricinoleate is basedon the elimination of odor; it binds/degrades chemical bonds ofunpleasant odorous substances in such a way that they are no longerperceivable. Yet it is also 100% natural and biodegradable as it is madefrom a castor oil extract. Castor oil is obtained by the cold pressingof seeds of the Ricinus communis plant followed by clarification of theoil by heat. Castor oil does not contain ricin because ricin is watersoluble and does not dissolve in the oil obtained from the castor beans.As a result, Castor oil is approved by the Food and Drug Administrationas a natural flavoring substance, as a direct food additive, and as asafe and effective stimulant laxative.

It will be appreciated that the aforementioned substance can beincorporated into one of the layers of the diaper 100 and can beincorporated into more than one layer of the diaper 100. In oneexemplary embodiment, the anti-odor technology is incorporated into theacquisition layer/absorbent core 300 by treating such material usingconventional processes including those mentioned herein with respect toapplying the surface treatments 305, 405.

Other options include crown ether, which is an odor-absorbing molecule,but this substance is synthetic and not biodegradable. Certain clays canabsorb odor, as can baking soda under certain conditions. However, zincricinoleate (as other similar metal salts) offer better performance thanthese alternatives since in a damp environment, zinc ricinoleate isactivated and absorbs odor more effectively than clays and baking sodas,which don't perform well when wet.

Another alternative is a cyclodextrin, which is currently used as asprayable odor absorber; however, it can be designed to be applied to atleast a portion of the diaper 100. Cyclodextrins work well; however,they are non-selective, unlike zinc ricinoleate, which prefers to damagenitrogen and sulfate bonds, and thus don't allow for any other volatilefragrances to be applied or incorporated into the final products.

The cyclodextrin molecule traps and binds volatilized hydrocarbonswithin its structural ring, retaining malodorous molecules, whichreduces their volatility and thus the perception of their scent. It alsobinds other pleasant odors as well. Thus, in an alternative embodiment,cyclodextrin can be directly applied during manufacture of the variouslayers of the end use product (e.g., diaper 100), so no after sprays arenecessary.

An alternative anti-odor technology involves adding non-hydrocarbonbased fragrances into nonwovens to impart malodor controlnon-selectively based on hydrocarbon de-volatilization and yet stilloffer fragrances that are not volatile hydrocarbon based, or are toolarge to bind, such as lavender or synthetic fresh and clean scents,synthetic powder scents, etc. These scents are still volatile enough tobe detected yet they are synthetically created to not be trapped instructure rings of cyclodextrin molecules or they are simply too largeof a molecule themselves for the cyclodextrins to bind and deactivate.

A third method is focused more on the application of fragrance to maskunpleasant odor, or simply create a more pleasant odor than notechnology, with softening agents or compounds applied like softeningagents. The softening compounds differ in affinity to differentmaterials. Some are better for cellulose-based fibers (e.g., cotton),others have higher affinity to hydrophobic materials like nylon,polyethylene terephthalate, polyacrylonitrile, etc.

Cyclodextrins, clays, and various fabric softeners are used as sprays orfor application during/after washing/drying durable fabrics (not onetime use nonwovens). They are available as solutions and solids,sometimes impregnated in dryer sheets to impart fragrance to mask malodor or add more pleasant odors to various surfaces. Cyclodextrins andclays are discussed in more detail above.

Silicone-based compounds such as polydimethylsiloxane comprise the newsofteners which work by lubricating the fibers. Derivatives with amine-or amide-containing functional groups are used as well. These groupshelp the softeners bind better to fabrics.

As the softeners themselves are often hydrophobic, they are commonlyoccurring in the form of an emulsion. In the early formulations, soapswere used as emulsifiers. The emulsions are usually opaque, milkyfluids. However, there are also microemulsions where the droplets of thehydrophobic phase are substantially smaller. The advantage ofmicroemulsions is in the increased ability of the smaller particles topenetrate into the fibers and better stability. A mixture of cationicand nonionic surfactants is often used as an emulsifier. Anotherapproach is using a polymeric network, an emulsion polymer.

Cationic Fabric Softeners

In the 1950s, distearyldimethylammonium chloride (DHTDMAC), wasintroduced as a fabric softener initially to counteract the harsh feelthat the machine washing imparted to diapers. This compound wasdiscontinued because the cation biodegrades very slowly. Contemporaryfabric softeners tend to be based on salts of quaternary ammoniumcations. Characteristically, the cations contain one or two long alkylchains derived from fatty acids. Other cationic compounds can be derivedfrom imidazolium, substituted amine salts, or quaternary alkoxy ammoniumsalts.

In an exemplary embodiment, distearyldimethylammonium chloride, a fabricsoftener with low biodegradability, may be used.

Anionic Fabric Softeners

Anionic softeners and antistatic agents can be, for example, salts ofmonoesters and diesters of phosphoric acid and the fatty alcohols. Theseare often used together with the conventional cationic softeners.Cationic softeners are incompatible with anionic surfactants used indetergents because they combine with them to form a solid precipitate.So, they must instead be added during the rinse cycle. Anionic softenerscan be combined with anionic surfactants directly. Other anionicsofteners can be based on smectite clays. Some compounds, such asethoxylated phosphate esters, have softening, anti-static, andsurfactant properties.

Zinc ricinoleate is a particularly preferred anionic softener. Zincricinoleate [Zn(Ri)2]is widely used in surfactant and detergent mixturesfor the adsorption of odor-active compounds. The mechanism of thisprocess is not fully known, however it reacts very well with nitrogenand some sulfate containing compounds. There are published studiesavailable, one study is found at: Journal of Surfactants and Detergents,July 2000, Volume 3, Issue 3, pp 335-343, Mechanism of theodor-adsorption effect of zinc ricinoleate. A molecular dynamicscomputer simulation H. Kuhn, F. Moiier, J. Peggau, R. Zekorn, thecontents of which are hereby incorporated by reference in its entirety.

Zinc ricinoleate or other cyclodextrins, salts, softening agents orderivatives can be applied by dip, pad, or spray bar to nonwovens duringthe manufacturing stage after fabric formation but before take-up.Typically, application is either just before, in a mid-stage, or justafter the dryers of the machinery. It is preferable to get as muchpossible uptake to have the least interference with other chemistries aspossible. In order to prevent molding of the fabric during storage andtransport, it is preferable that the fabric is fully formed and thistechnology dried before rolls are created and bagged for storage.

In accordance with one exemplary embodiment of the present invention, adeodorizing composition for use with the absorbent articles describedherein has the following formulation:

-   -   between 0.1% and 10% of a zinc, copper, silver or aluminum salt,        most preferably zinc rincinoleate, and/or    -   a binder consisting of individual components or a combination of        the following; ethoxylated alcohols, ethoxylated glycols,        ethoxylated oils, polymers or co-polymers of acrylic acid        (including methacrylic acid); and/or    -   coupling agents consisting of individual components or a        combination of the following; ethoxylated alcohols, ethoxylated        glycols, ethoxylated oils polymers or copolymers of acrylic acid        (including methacrylic acid), and/or drying agents consisting of        any primary, secondary, or tertiary alcohol or solvent        (including any ketone).

The above anti-odor composition can be carried in either an aqueous orsolvent based system.

In one preferred embodiment, the deodorizing composition has thefollowing formulation (listed by weight percentages):

Ingredient % w/w Zinc Rincinoleate (deodorant) 2.00 Cetyl Alcohol(thickener, emollient) 2.50 Glyceryl stearate and PEG-100 4.00stearate - Acid-Stable (emulsifier) Triglyceride (emollient) 4.00Ceteareth-20 (emulsifier) 2.00 Polyglyceryl Oleate (emulsifier) 1.00distilled water 76.00 citric acid 0.01 ethyl alcohol 9.00

FIGS. 7-9 illustrate another absorbent article (e.g., a diaper) 600 inaccordance with the present invention. The diaper 600 includes many, ifnot all, of the layers described hereinbefore with respect to otherabsorbent article products. As with the previous embodiments, the diaper600 is a biodegradable product and more specifically and preferably, isat least substantially 100% biodegradable.

It will be appreciated that while the construction 600 is described andshown as being a diaper, the construction 600 can be implemented inother absorbable products, such as those described herein.

Inner Layer

Diaper 600 includes inner layer (top sheet) 200. In FIG. 7, the innerlayer 200 is shown partially folded back in order to expose andillustrate the other layers of the diaper 600. The inner layer 200 canbe formed of any of the materials disclosed hereinbefore. Thus, theinner layer 200 is formed a biodegradable material and in theillustrated embodiment, the inner layer 200 is formed of cotton (e.g., anonwoven cotton).

As mentioned above, a surface treatment can be applied to the innerlayer 200 to impart hydrophobicity or hydrophilicity. In certainpreferred embodiments, the inner layer 200 is hydrophobic.

As shown in FIG. 7, the inner layer 200 can be in the form of a sheetand more particularly, can have a gauze like structure (e.g. cottongauze structure). As is known, a gauze is a thin fabric with a looseopen weave. The term “gauze” actually refers to a weave structure inwhich the weft yarns are arranged in pairs and are crossed before andafter each warp yarn, thereby keeping the weft firmly in place. Thisconstruction allows fluid to rapidly travel away from baby's skin andinto the absorbent core 300.

The inner layer 200 is thus a soft, comfortable barrier layer formed ofa biodegradable material.

ADL Construction

Below the inner layer 200 in FIG. 7 is an acquisition distribution layer(ADL) 610. As mentioned previously, the ADL is an optional component(layer) in the diaper 600 and therefore, while the diaper 600 is shownas including ADL 610, it will be appreciated that such layer can beeliminated from the diaper 600. The ADL 610 can be formed of any numberof different materials that perform the intended function (fluidacquisition and distribution to another layer (i.e., the absorbentcore)) including those mentioned herein before and in one embodiment,the ADL 610 is in the form of a biodegradable sheet, such as one formedof a natural material. The ADL 610 can thus be in the form of cottonfabric material (e.g., a nonwoven cotton sheet) and/or PLA. Aspreviously mentioned, the ADL of a conventional diaper has a syntheticconstruction in that it is formed of polypropylene/polyethylene (PP/PE)and is thus not biodegradable. In preferred embodiments, the ADL iscomprised of PLA.

In certain embodiments, the footprint of the inner layer 200 ispreferably greater than the footprint of the ADL 610 as shown. As aresult, when the inner layer 200 is laid over the ADL 610, the innerlayer 200 completely covers and extends outwardly beyond the peripheraledges of the ADL 610 (i.e., the inner layer 200 overhangs the edges ofthe ADL 610).

In other preferred embodiments of a diaper, the footprint of the innerlayer is coextensive with the footprint of the ADL 610. In theseembodiments, the ADL expands across the width of the diaper from one legcuff 500 to the other. This construction keeps any SAP from leaking intothe diaper or onto baby's skin if the 620 core wrap were to break.

In preferred embodiments, the inner layer is adhered to the ADL with anadhesive, such as a glue. It is preferred that the adhesive is onlyapplied to the peripheral edges of the ADL. Over application of adhesiveto either the ADL or inner layer can negatively affect the movement offluid into the ADL/core and impart a feeling of wetness against theskin.

Absorbent Core Structure

The diaper 600 includes an absorbent core structure which is formed atleast of an absorbent core 605 and optionally, also includes anabsorbent core wrap 620 that encapsulates and contains the material(s)forming the absorbent core 605. As described herein, the absorbent corewrap 620 can be shaped so as to impart a shape to the overall structure.The absorbent core structure is located adjacent either the inner layer200 or the ADL 610 if present.

The absorbent core wrap 620 can be formed of any number of differentmaterials and can be provided in any number of different shapes.Suitable biodegradable materials have been discussed hereinbefore. Forexample, the absorbent core wrap 620 can be formed of natural fibers,such as, cotton or can be formed of other natural fibrous materials,such as wood pulp or the like. Thus, according to one exemplaryembodiment, the absorbent core wrap 620 can be formed of cotton and canbe formed so as to define a hollow interior space that receives theabsorbent core 605, namely, the SAP and pulp. The absorbent core wrap620 can thus be in the form of a wrap or envelope structure thatcontains the SAP and pulp. Exemplary shapes of the absorbent core wrap620 are discussed below.

In one embodiment, the absorbent core wrap 620 is treated with ahydrophilic agent, such as those described herein, so as to increase thehydrophilicity of the wrap 620 and allow the wrap 620 to push themoisture (fluid) to the inner material (absorbent core) containedtherein (which by nature is very hydrophilic in nature).

More specifically and according to one embodiment, the absorbent corewrap 620 can be a cotton non-woven and can optionally include apolyvinyl acetate (PVA) binder sprayed with a wicking agent. Use ofcotton as the absorbent core 620 provides a thicker absorbent corestructure which allows for the elimination of the optional ADL material.The absorbent core wrap 620 is the mechanism by which the SAP and pulpare contained and transfer moisture quickly to those membranes (the SAPand pulp) which forms the absorbent core 605.

In some embodiments, the core is adhered to the ADL and/or the innerlayer with an adhesive, such as a glue. It is preferred that theadhesive is only applied to the peripheral edges of the core. Overapplication of adhesive to either the core, ADL or inner layer cannegatively affect the movement of fluid into the ADL/core and impart thefeeling of wetness against the skin.

SAP

As mentioned above, the absorbent core wrap 620 can take any number ofdifferent shapes. For example, it can be similar to a pillow case (withclosed ends) in that it has a top layer and an opposing bottom layerthat are joined so as to create a hollow interior for receiving theinternal components, namely and for example, SAP and pulp.Alternatively, the absorbent core wrap 620 can have the constructionshown in FIG. 7 and more specifically, the absorbent core wrap 620 canbe a corrugated shaped core with a hollow interior that receives theinternal components. The corrugated core wrap 620 shown in FIG. 7 isdefined by a series of peaks 622 and alternating valleys 624. Thevalleys define channels for moving moisture quickly. The channels andvalleys are arranged longitudinally along the length of the absorbentcore wrap 620. It will be appreciated that the size and number ofchannels can vary.

Alternatively, the absorbent core wrap 620 can be formed from a papermaterial (cellulose pulp). The paper absorbent core wrap 620 offersexcellent performance and does not require any chemical treatment. Anynumber of different paper based materials can be used so long as theyare suitable for the intended application. When the absorbent core wrap620 is formed of paper, the hollow interior defined therein is stillfilled with other absorbent materials, such as those describes above(e.g., SAP and pulp). It will be appreciated that this alternativeabsorbent core wrap 620 is likewise biodegradable.

As mentioned above, one of the components that is disposed within theabsorbent core wrap 620 and makes up the absorbent core 605 is SAP. TheSAP that is used in combination with absorbent core wrap 620 can be anyof the SAP materials discussed herein. For example, the SAP can be inthe form of 100% acrylic acid coacrylamide with little to no shell. Asis known, the shell of the SAP constitutes more tightly crosslinkedpolymer relative to the center core of the shell.

The reduction or elimination of the SAP shell provides for abiodegradable SAP and allows for the entire diaper 600 to beenvironmentally friendly (i.e., biodegradable).

In an alternative embodiment, the SAP can be in the form of acrylic acidcoacrylamide (with little to no shell) combined with anotherbiodegradable material, such as starch from corn, potato, yams or otherstarch-rich plants. For example, the SAP can be a mixture of acrylicacid co-acrylamide (with little to no shell) with corn starch. Thepercentage of each component can vary depending upon the application andalso based on other considerations. In general and according to oneembodiment, each component can be present in an amount from 10% to 90%of the overall total (by weight), with the weight percentages of all ofthe components adding up to 100% (however, this is merely an exemplaryembodiment and others are equally possible including those outside thisrange).

In yet another embodiment, the absorbent core 605 can eliminate the useof SAP as a part thereof and instead can be based on a 100%biodegradable material, such as starch from corn, potato, yams or otherstarch-rich plants. For example, 100% corn starch can be used as theabsorbent core 605 in the interior of the absorbent core wrap 620. Thecorn starch can also be mixed with another different biodegradablematerial, such as cotton lint or other natural fibrous material.

In yet a further embodiment, the absorbent core 605 can contain 100%clay (attapulgite which is technically magnesium aluminum phyllosilicate(MgAl)₂Si₄O₁₀(OH)+4 H₂O). The clay is similarly disposed within thehollow interior of the absorbent core 605.

As will be understood, when the absorbent core 605 consists of a naturalmaterial, such as pulp/fluff, and SAP, the pulp/fluff serves to hold andspace out the SAP so that the SAP is not all in one loose mass at thelowest point in the absorbent article. By distributing the SAP acrossthe absorbent article structure, the absorbency of the SAP is optimized.

Film Layer

Optionally, a film 630 can be provided and disposed adjacent theabsorbent core structure on the rear side thereof. The film 630 is thusdisposed in contact with the absorbent core structure (e.g., the wrap620 when present). As shown in FIG. 7, the film 630 can have a largerfootprint than the absorbent core structure. The film 630 thus extendscompletely around the absorbent core structure (extends outwardly fromthe peripheral edges of the absorbent core structure). In oneembodiment, the footprint of the film 630 is about the same as thefootprint of the absorbent core structure.

Traditional films used in conventional diaper constructions are formedtypically of nonwoven polypropylene/polyethylene (PP/PE). As with theother components of diaper 600, the film 630 is formed of abiodegradable material. For example, the film 630 can be formed of apolylactic acid (PLA) or polylactide biodegradable thermoplasticmaterial. Incorporation of a PLA film 630 facilitates printing ofdesigns onto the back sheet 400.

In preferred embodiments, the film is adhered to the outer layer with anadhesive, such as a glue, or by thermal or ultrasonic methods. It ispreferred that the film is only adhered to other layers at theperipheral edges of the film. Over application of adhesive or bondingmeans can negatively affect the movement of fluid into the ADL/core.

Once again, the film 630, which acts as a barrier, is optional.

Leg Cuffs

The diaper also includes a pair of leg cuffs 500 that are designed toeffectively prevent leakage at the sides of the diaper 600, therebykeeping the infant's skin dry and protected. As with the othercomponents, the leg cuffs 500 are formed of a biodegradable material.Any number of biodegradable materials, including those described herein,can be used to form the leg cuffs 500. For example, the leg cuffs 500can be formed of cotton (nonwoven) or other natural material.

Each leg cuff 500 has an associated elastic element 501 to ensureimproved fit around the legs and prevent leakage. The elastic element501 can be formed of a suitable material, such as a natural rubber,biodegradable rubber, or a biodegradable polymer. As in traditionaldiapers, the elastic element 501 extends along a length of the leg cuff500 and creates a cuff gather in a central location of the cuff 500 asshown in FIG. 8.

Back Sheet/Cover

As with the previous diapers, the diaper 600 includes back sheet orcover 400 which represents the outer layer of the diaper 100 and isconstructed to prevent liquids from leaking out of the diaper 100. Theback sheet 400 thus acts as an outer cover. As shown in FIG. 7, the backsheet 400 typically has a footprint that is greater than those of theother components including the inner layer 200.

As mentioned, it is preferable that the other layers of diaper 600 arebonded or adhered to each other and/or the back sheet at the peripheraledges the respective layers. Over application of adhesive or bondingmeans can negatively affect the movement of fluid into the ADL/core.

In accordance with the present invention, the back sheet 400 is alsoformed from natural materials and in particular, is a nonwoven structureformed from natural fibers, such as those listed herein or othersuitable biodegradable materials. The inner layer 200 and the back sheet400 can be formed of the same material. In one exemplary embodiment, theback sheet 400 is a nonwoven cotton structure that is constructed toprovide a fluid impervious layer.

The back sheet 400 can be hydrophobically treated and in particular, thenonwoven material forming the back sheet 400 can undergo a surfacetreatment using a treatment composition which either imparts hydrophobicproperties. Any number of different surface treatments can be used toimpart increased hydrophobicity to the nonwoven fabric. For example,certain agents can increase the hydrophobic nature of the material andmore particularly, materials, such as urethanes, silicones,fluorocarbons, non-fluorochemical repellents and waxes, can imparthydrophobic properties. The surface treatment can be performed using anynumber of suitable techniques and more specifically, conventionaltreatments involve steps such as dipping the nonwoven in a treatmentbath, coating or spraying the nonwoven with the treatment composition,and printing the nonwoven with the treatment composition.

At least in some embodiments, back sheet 400 can be used by itself withno other barrier films and/or surface treatments.

Other details concerning the back sheet 400 are discussed herein withreference to other diaper constructions, such as diaper 100.

As shown in FIG. 9, the diaper 600 can contain a wetness indicator 700.Wetness indictor 700 is a feature that reacts to exposure of liquid as away to discourage the wearer to urinate in the training pants, or as anindicator for parents that a diaper needs changing. The wetnessindicator 700 can be of a type which “fades when wet” meaning that thewetness indicator 700 fades as a reaction to liquid, specifically urine.The wetness indicator 700 is shown as being a stripe; however, it willbe appreciated that this is merely an exemplary graphic and others areequally possible.

It should be understood that the foregoing is illustrative and notlimiting, and that obvious modifications may be made by those skilled inthe art without departing from the spirit of the invention. Accordingly,reference should be made primarily to the accompanying claims, ratherthan the foregoing specification, to determine the scope of theinvention.

What is claimed is:
 1. A disposable absorbent article comprising: anon-woven inner layer consisting of 100% cellulosic fibers; ahydrophobic non-woven outer layer, the hydrophobic non-woven outer layerconsisting of: a) 100% cellulosic fibers treated with an internalhydrophobic agent, the internal hydrophobic agent is a dendrimer wax;and b) an external hydrophobic surface treatment applied to a surface ofthe non-woven outer layer, the external hydrophobic surface treatmentselected from the group consisting of waxes, urethanes, silicones,fluorocarbons, non-fluorochemical repellents, and combinations thereof,and a core comprising natural fibers or fibrous material positionedbetween the non-woven inner layer and the non-woven outer layer.
 2. Theabsorbent article of claim 1, wherein the absorbent article is selectedfrom the group consisting of: diapers, nappies, absorbent underpants,training pants, adult incontinence products, pet incontinence products,feminine hygiene products, wound dressings, and breast pads.
 3. Theabsorbent article of claim 1, wherein the core comprises polyacrylatesuperabsorbent particles (SAP).
 4. The absorbent article of claim 1further comprising an acquisition/distribution layer comprised ofpolylactic acid between the non-woven inner layer and the core.
 5. Theabsorbent article of claim 4, wherein the acquisition/distribution layerincludes a deodorizing composition comprising between about 0.1% andabout 10% of a zinc, copper, silver or aluminum salt.
 6. The absorbentarticle of claim 5, comprising about 0.1% and about 10% zincricinoleate.
 7. The absorbent article of claim 6, wherein thedeodorizing composition further comprises at least one compound selectedfrom the group consisting of ethoxylated alcohols, ethoxylated glycols,ethoxylated oils, polymers or co-polymers of acrylic acid andcombinations thereof; and at least one drying agent selected from thegroup consisting of primary, secondary, and tertiary alcohols andcombinations thereof.
 8. The absorbent article of claim 1, wherein thecore comprises a corrugated structure defined by a plurality of peaksand valleys.
 9. The absorbent article of claim 1, wherein the corecomprises a non-woven wrap surrounding loose fibers.
 10. The absorbentarticle of claim 1, wherein the non-woven inner layer includes aplurality of pores.
 11. The absorbent article of claim 1 furthercomprising an acquisition/distribution layer comprised of at least oneof cotton and natural fibers between the non-woven inner layer and thecore.
 12. The absorbent article of claim 1, wherein the core comprises apaper wrap surrounding loose fibers.
 13. The absorbent article of claim1, wherein the cellulosic fibers are selected from the group consistingof cotton, hemp, flax, ramie, rayon, bamboo, and combinations thereof.14. A biodegradable diaper comprising: a non-woven inner layerconsisting of 100% cotton; a hydrophobic non-woven outer layer, thehydrophobic non-woven outer layer consisting of: a) 100% cotton treatedwith an internal hydrophobic agent, the internal hydrophobic agent is adendrimer wax; and b) an external hydrophobic surface treatment appliedto a surface of the non-woven outer layer, the external hydrophobicsurface treatment selected from the group consisting of waxes,urethanes, silicones, fluorocarbons, non-fluorochemical repellents, andcombinations thereof, and an absorbent core comprising polyacrylatesuperabsorbent particles and at least one of cotton and fluff pulppositioned between the non-woven inner layer and the non-woven outerlayer.
 15. The diaper of claim 14, wherein the non-woven inner layerincludes a plurality of pores.
 16. The diaper of claim 14, furthercomprising a polylactic acid film disposed between at least one of thecore and the non-woven outer layer or the core and the non-woven innerlayer.
 17. The diaper of claim 14, further comprising a pair of lateralflaps extending from a rear portion of the non-woven outer layer, saidflaps including polylactic acid fasteners capable of affixing the flapsto a front portion of the non-woven outer layer.
 18. The diaper of claim14, wherein the diaper passes at least one of ASTM Test Method D5511-12,ASTM Test Method 5338-15, and ISO CD Test Method 14855-1:2012.
 19. Adisposable absorbent article comprising: a non-woven inner layerconsisting of 100% cellulosic fibers; a hydrophobic non-woven outerlayer, the hydrophobic non-woven outer layer consisting of: (a) 100%cellulosic fibers treated with an internal hydrophobic agent, theinternal hydrophobic agent is a dendrimer wax; and (b) an externalhydrophobic surface treatment applied to a surface of the non-wovenouter layer, the external hydrophobic surface treatment selected fromthe group consisting of waxes, urethanes, silicones, fluorocarbons,non-fluorochemical repellents, and combinations thereof; and a corepositioned between the non-woven inner layer and the non-woven outerlayer, the core comprising: a corrugated absorbent structure ofabsorbent material comprising natural fibers or fibrous material, thecorrugated absorbent structure having a plurality of alternating peaksand valleys, the plurality of alternating peaks and valleys providing afluid retainment space in the core.